Its probably a natural defect in the stick, it may have not had any repairs . cracks like this can be present in pernambuco whilst making bows and often are only visible when heated to camber the bow, they can be very problematic if they are going right through the stick or especially if they are running out at a angle . This looks perfectly straight with no run out.
Ive seen bows by top French makers like Peccatte which appear to have had these type of defects from new but they are usually visible on the top or hair side of the stick.
What direction is the grain running in the wood ,usually visible on the back of the head ?
It is more usual in the bows ive seen to have cracks in this direction. See pic. It may be troublesome if you get it recambered .